Injection Volume Adjustment
The injection volume is adjusted by operating the SPV in accordance with the signals from the ECU to vary the timing of the ending of the injection.
Injection Timing Construction of TCV (Timing Control Valve)
The construction of the timing control valve is shown in the illustration in the left.
The construction of the timer is shown in the illustration in the left.
Operation of Timer of Axial Plunger Type Pump
The TCV valve is controlled by the ratio (duty-cycle ratio) of the ON/OFF time of the current that is applied to the coil. The length of time that the valve remains open, with the current ON, controls the fuel pressure in the timer piston.
Advance
When the length of time that the valve remains open is short (the ratio of the current being applied is low), the amount of fuel that is bypassed becomes smaller. Thus, the timer piston moves to the left to rotate the roller ring in the direction of timing advance.
Retard
When the length of time that the valve remains open is long (the ratio of the current being applied is high), the amount of fuel that is bypassed becomes greater. Thus, the timer piston moves to the right by the force of the spring to rotate the roller ring in the direction of timing retard.
Operation of Timer of Radial Plunger Type Pump
The TCV valve is controlled by the ratio (duty-cycle ratio) of the ON/OFF time of the current that is applied to the coil. The length of time that the valve remains open, with the current ON, controls the fuel pressure in the timer piston.
Advance
When the length of time that the valve remains open is short (the ratio of the current being applied is low), the amount of fuel that is bypassed becomes smaller. Thus, the timer piston moves to the left to rotate the roller ring in the direction of timing advance.
Retard
When the length of time that the valve remains open is long (the ratio of the current being applied is high), the amount of fuel that is bypassed becomes greater. Thus, the timer piston moves to the right by the force of the spring to rotate the roller ring in the direction of timing retard.